Method of Uplink Multi-Cell Joint Detection in a Time Division-Synchronous Code Division Multiple Access System

ABSTRACT

The present invention discloses a method for uplink multi-cell joint detection in a Time Division-Synchronous Code Division Multiple Access system to realize uplink multi-cell joint detection by a Node B. The method comprises: a radio network controller sending neighbor cell channel updating information to neighbor Node Bs of a cell where a user terminal is located when a Node B application part protocol process happens at an Iub interface to establish a radio link for the user terminal; and the neighbor Node Bs adding information of the user terminal into an uplink multi-cell joint detection information of the cell where uplink joint detection is required to be performed for the user terminal after receiving the neighbor cell channel updating information. The method of the present invention realizes uplink multi-cell joint detection by a Node B.

TECHNICAL FIELD

The present invention relates to wireless communication systems, andmore particularly, to a method for uplink multi-cell joint detection ina Time Division-Synchronous Code Division Multiple Access (TD-SCDMA)system.

TECHNICAL BACKGROUND

Since Code Division Multiple Access (CDMA) system is a self-interferencesystem, in the TD-SCDMA system, the interference between users limitsfurther improvement of quality of service (QoS). Thus, a user equipment(UE) implements joint detection for its cell in downlink; while a Node B(base station) implements joint detection for its cell in uplink.

In 3GPP 25.331RRC (radio resource control) protocol, scrambling codeinformation of neighbor cells is carried in a same-frequency measurementcontrol message. Therefore, the UE may implement blind detection forneighbor cells in downlink as long as it has ability enough to do so.However, in 3GPP 25.433NBAP (Node B application part) protocol, sinceinformation of any of the neighbor cells is unable to be provided tocells of the Node B, the Node B cannot implement multi-cell jointdetection in uplink. For users of other neighbor cells, especially inthe vicinity of a switching zone, the interference caused by the UE cannot be eliminated in its cell, thus, uplink transmission power of the UEin this cell will be increased in order to ensure QoS of the users, andusers in other cells will raise the power accordingly, which results inthe vicious circle and instability of the whole system.

SUMMARY OF THE INVENTION

A technical problem to be solved by the present invention is to providea method for uplink multi-cell joint detection in order for Node B toimplement the uplink multi-cell joint detection in a TD-SCDMA system.

In order to solve the technical problem described above, the presentinvention provides a method for uplink multi-cell joint detection in aTime Division-Synchronous Code Division Multiple Access (TD-SCDMA)system comprising:

a radio network controller sending neighbor cell channel updatinginformation to neighbor Node Bs of a cell where a user terminal islocated when a Node B application part protocol process happens at anIub interface to establish a radio link for the user terminal; and

the neighbor Node Bs adding information of the user terminal into uplinkmulti-cell joint detection information of the cell where uplink jointdetection is required to be performed for the user terminal afterreceiving the neighbor cell channel updating information.

The method may further comprise:

the radio network controller sending the neighbor cell channel updatinginformation to the neighbor Node Bs when notifying a Node B where theuser terminal is located to reconfigure the radio link; and

the neighbor Node Bs receiving the neighbor cell channel updatinginformation, and updating the information of the user terminal in theuplink multi-cell joint detection information.

The method may further comprise:

the radio network controller sending neighbor cell channel deletioninformation to the neighbor Node Bs when the Node B application partprotocol process happens at the Iub interface to delete the radio linkof the user terminal; and

the neighbor Node Bs deleting the information of the user terminal inthe uplink multi-cell joint detection information after receiving theneighbor cell channel deletion information.

Further, the neighbor cell channel deletion information may include auser terminal identifier.

In the method, the Node B application part protocol process to establishthe radio link for the user terminal may include a radio link setupprocess or a radio link addition process.

In the method, the neighbor Node Bs of the cell where the user terminalis located are Node Bs where cells which are found from neighbor cellsof the cell where the user terminal is located are located, the neighborNode Bs including a cell which contains a frequency point at which theestablished radio link is present and is also the cell where uplinkjoint detection is required to be performed for the user terminal.

In the method, the neighbor cell channel updating information mayinclude a user terminal identifier as well as a carrier frequency onwhich the established radio link is present and a physical channeloccupied by the established radio link.

Further, the neighbor cell channel updating information may also includescrambling codes of the cell where the user terminal is located and alist of cells where uplink joint detection is required to be performedby the neighbor Node Bs.

Using the method for uplink multi-cell joint detection in accordancewith the present invention may cause the Node B to implement the uplinkmulti-cell joint detection so as to eliminate interference informationbetween the UEs in neighbor cells and improve system capacity andquality of service (QoS) while reducing greatly Iub interface messages.Furthermore, the more the Node Bs are, the more obvious the effect is.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flow chart of steps of an example of the method ofthe present invention;

FIG. 2 illustrates a flow chart of steps of an application example ofthe method of the present invention;

FIG. 3 illustrates a schematic diagram of an application scenario ofthree Node Bs including a total of 9 cells; and

FIG. 4 illustrates a flow chart of steps of another application exampleof the method of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

The present invention will be further described in detail below inconjunction with the accompanying drawings and the preferredembodiments.

FIG. 1 illustrates a flow chart of steps of an example of the method ofthe present invention comprising steps:

step 101: a radio network controller (RNC) sends neighbor cell channelupdating information to neighbor Node Bs of a cell where a user terminalis located when a process to establish a radio link for the user happensat an Iub interface;

step 102: the neighbor Node Bs update uplink multi-cell joint detectioninformation;

step 103: the RNC sends neighbor cell channel deletion information tothe neighbor Node Bs; and

step 104: the neighbor Node Bs remove the user from joint detection anddelete the joint detection message of the user.

In the step 101, the determination process for the neighbor Node Bs isto find a cell containing a frequency point at which the establishedradio link is present from neighbor cells configured for the cell wherethe user terminal is located (which will be referred to as the currentcell hereinafter). Node Bs where these cells are located are theneighbor Node Bs.

Assuming that the frequency point at which a NBAP process to establishthe radio link is initiated in the current cell is F, a neighbor cellset comprised of all the neighbor cells of the current cell is S,S={Cell1, Cell2, . . . Cello}, where o is the number of elements in theneighbor cell set S.

If there is the frequency point F in Celli (i≦o) in S, then the cellCelli is put into a same-frequency neighbor set Sc={Cell1, Cell2,Cellp}, where p represents the number of elements in the set Sc, p≦o.The neighbor cells in the set Sc are classed by the Node Bs where theyare located, that is, the neighbor cells which are located in the sameNode B are classed into the same set:

-   -   Sni={Cellni_1, Cellni_2, . . . Cellni mi}, where i=0, 1, q,        where Sni represents a set of the neighbor cells of the current        cell in Node B; q represents the number of elements of the set        Sn, qp; mi represents the number of

${\sum\limits_{i = 1}^{q}{mi}} = {p.}$

eLements of the set Sni, m≧1; Sni∩Snj=φ, where i≠j, i,j≧q; and

The frequency point of the NBAP process is the frequency point at whichthe radio link established in the NBAP process is present. The neighborcell channel updating information includes a UE identifier (e.g., whichmay be CRNC CCID), a carrier frequency on which the established radiolink is present and a physical channel occupied by the established radiolink. The neighbor channel updating message may further includescrambling codes of the cell where the UE is located and informationregarding to a list of cells where uplink joint detection is required tobe performed by the neighbor Node Bs.

In the above example of the present invention, the process happening atthe Iub interface to establish the radio link for the user includesradio link setup or radio link addition. The present invention will bedescribed specifically below using two application examples for theradio link setup.

FIG. 2 illustrates a flow chart of steps of an application example ofthe method of the present invention. A synchronized radio linkreconfiguration commit process for reconfiguring the radio link isfurther included in this application example to describe the presentinvention in more detail. Steps in this application example will bedescribed below.

Step 201: a user U (whose UE identifier is U) initiates radio resourcecontrol (RRC) connection setup and a RNC decides to establish the RRCconnection of the UE in a dedicated channel (DCH) status to establish aradio link (RL) at an Iub interface.

Step 202: after the radio link setup is completed, the RNC sendsneighbor cell channel updating information to neighbor Node Bs.

Based on a schematic diagram of an application scenario of the presentinvention as shown in FIG. 3, a determination principle for neighborNode Bs in this step is described as follow.

As shown in FIG. 3, there is a total of three Node Bs (Node B N1, Node BN2 and Node B N3) in the application scenario, each Node B being a cellwith three-carrier (F1, F2 and F3) three-sector configuration (each NodeB having 3 cells and each cell having 3 carriers). Thus, there are 9cells (C11, C12, C13; C21, C22, C23; C31, C32, C33) in total, which areneighbor cells relative to each other.

If the radio link of the user U is established in the cell C11, afrequency point is F1, a scrambling code is M1 and a channelization codeis CC16/1, then a set comprised of all the neighbor cells of the currentcell (i.e., the cell C11) is a neighbor cell set S={C12, C13, C21, C22,C23, C31, C32, C33}, where the number of elements of the set S is 8. Thefrequency point F1 exists in each cell in the set S, thus, each cell inS is put into a same-frequency neighbor cell set Sc. In this applicationexample, Sc=S, p represents the number of elements of the set Sc, p=8.The neighbor cells in the set Sc are classed by the Node Bs where theyare located, that is, the neighbor cells which are located in the sameNode B are classed into the same set:

Sn1={C12, C13}, m1=2;

Sn2={C21, C22, C23}, m2=3;

Sn3={C31, C32, C33}, m3=3;

where:

Sni⋂Snj = φ,  where  i ≠ j, i, j3;${\sum\limits_{i = 1}^{q}{mi}} = {p.}$

The RNC sends neighbor cell channel updating information, which containsthe UE identifier U, the scrambling code M1 of the cell where the useris located, the carrier frequency F1 on which the established radio linkis present, the physical channel CC16/1 occupied by the establishedradio link and information regarding to a list of cells where uplinkjoint detection is required to be performed by the neighbor Node Bs, toN1, N2 and N3, respectively.

For neighbor Node B N1, the list of the cells where joint detection isperformed includes C12 and C13; for neighbor Node B N2, the list of thecells where joint detection is performed includes C21, C22 and C23; andfor neighbor Node B N3, the list of the cells where joint detection isperformed includes C31, C32 and C33.

Step 203: the neighbor Node Bs receive the neighbor cell channelupdating information to update uplink multi-cell joint detectioninformation.

In this step, for N1, if the user U does not exist, information of theuser is newly created to be added into an uplink joint detection processfor the cell C12 and C13; for N2, if the user U does not exist,information of the user is newly created to be added into an uplinkjoint detection process for C21, C22 and C23; and for N3, if the user Udoes not exist, information of the user is newly created to be addedinto an uplink joint detection process for C231, C32 and C33.

Step 204: a core network (CN) transmits a radio access bearer (RAB)assignment, and the RNC reconfigure the radio link at the Iub interfaceduring a radio bearer (RB) setup process.

Step 205: after transmitting the synchronized radio link reconfigurationcommit message to a Node B where the user U is located, the RNC sendsthe neighbor cell channel updating information to neighbor node Bs.

If the RL of the user U is reconfigured in the cell C11, the frequencypoint is F1, the scrambling code is M1 and the channelization code ischanged to CC8/1, then the RNC sends neighbor cell channel updatinginformation to N1, N2 and N3, respectively, with the UE identifier U,the scrambling code M1 of the cell where the user is located, thecarrier frequency F1, the physical channel information CC8/1 in eachpiece of neighbor cell channel updating information being the same,respectively. For the list of cells where uplink joint detection isrequired to performed by the neighbor Node Bs, the step 202 may bereferred to.

Step 206: the neighbor Node Bs receive the neighbor cell channelupdating information to update the uplink multi-cell joint detectioninformation.

In this step, for N1, if the user U exists, the information of the useris updated to update the uplink joint detection process for the cell C12and C13; for N2, if the user U exists, the information of the user isupdated to update the uplink joint detection process for C21, C22 andC23; and for N3, if the user U exists, the information of the user isupdated to update the uplink joint detection process for C31, C32 andC33.

Step 207: when a call from the UE terminates, the CN triggers an Iurelease process and the RNC performs a RRC release and a radio linkdeletion process.

Step 208: the RNC sends a neighbor channel deletion message containingthe user identifier U to N1, N2 and N3, respectively.

For N1, the uplink joint detection process for the cell C12 and C13 isupdated and the information of the user U in the joint detection messageis deleted; for N2, the uplink joint detection process for C21, C22 andC23 is updated and the information of the user U in the joint detectionmessage is deleted; and for N3, the uplink joint detection process forC231, C32 and C33 is updated and the information of the user U in thejoint detection message is deleted.

It can be seen from this application example that updating the uplinkmulti-cell joint detection information comprises adding or deleting theinformation of the user terminal in the uplink multi-cell jointdetection information and modifying the information of the user terminalin the uplink multi-cell joint detection information.

Still based on the schematic diagram of the application scenario of thepresent invention as shown in FIG. 3, FIG. 4 illustrates a flow chart ofsteps of another application example of the method of the presentinvention. The steps will be described below.

Step 401: a user U initiates RRC connection setup and a RNC decides toestablish the RRC connection of the UE in a forward access channel(FACT-1) status.

Step 402: a CN transmits a RAB assignment and the RNC performs a RBsetup process to establish a radio link at an Iub interface.

Step 403: after the radio link setup is completed, the RNC sendsneighbor cell channel updating information to neighbor Node Bs. For theprocessing of the neighbor Node Bs in this step, the step 202 may bereferred to. If the RL of the user U is established in the cell C11, thefrequency point is F1, the scrambling code is M1 and the channelizationcode is CC8/1, then the RNC sends neighbor cell channel updatinginformation to N1, N2 and N3, respectively, with the UE identifier U,the scrambling code M1 of the cell where the user is located, thecarrier frequency F1, the physical channel information CC8/1 in eachpiece of neighbor cell channel updating information being the same,respectively.

For neighbor Node B N1, the list of the cells where joint detection isperformed includes C12 and C13; for neighbor Node B N2, the list of thecells where joint detection is performed includes C21, C22 and C23; andfor neighbor Node B N3, the list of the cells where joint detection isperformed includes C31, C32 and C33.

Step 404: the neighbor Node Bs receive the neighbor cell channelupdating information to update uplink multi-cell joint detectioninformation.

In this step, for N1, if the user U does not exist, the information ofthe user is newly created to be added into an uplink joint detectionprocess for the cell C12 and C13; for N2, if the user U does not exist,the information of the user is newly created to be added into an uplinkjoint detection process for C21, C22 and C23; and for N3, if the user Udoes not exist, the information of the user is newly created to be addedinto an uplink joint detection process for C31, C32 and C33.

Step 405: when a call from the UE terminates, the CN triggers an lurelease process and the RNC performs a RRC release and radio linkdeletion process.

Step 406: the RNC sends a neighbor channel deletion message containingthe user identifier U to N1, N2 and N3, respectively.

In this step, for N1, the uplink joint detection process for the cellC12 and C13 is updated and the information of the user U in the jointdetection message is deleted; for N2, the uplink joint detection processfor C21, C22 and C23 is updated and the information of the user U in thejoint detection message is deleted; and for N3, the uplink jointdetection process for C31, C32 and C33 is updated and the information ofthe user U in the joint detection message is deleted.

Using the method for uplink multi-cell joint detection in accordancewith the present invention can implement the uplink multi-cell jointdetection at the Node B. According to the principle of joint detection,the method in accordance with the present invention eliminatesinterference information between the UEs in neighbor cells and improvessystem capacity and quality of service (QoS) while reducing greatly Iubinterface messages. Furthermore, the more the Node Bs are, the moreobvious the effect is.

Various modifications may be made to the embodiments described above bythose skilled in the art without departing from the spirit and scope ofthe present invention defined by the appended claims. Therefore, thescope of the present invention is not limited to the above description,but is defined by the scope of the claims.

1. A method for uplink multi-cell joint detection in a TimeDivision-Synchronous Code Division Multiple Access system comprising: aradio network controller sending neighbor cell channel updatinginformation to neighbor Node Bs of a cell where a user terminal islocated when a Node B application part protocol process happens at anIub interface to establish a radio link for the user terminal; and theneighbor Node Bs adding information of the user terminal into an uplinkmulti-cell joint detection information of the cell where uplink jointdetection is required to be performed for the user terminal afterreceiving the neighbor cell channel updating information.
 2. The methodaccording to claim 1, further comprising: the radio network controllersending the neighbor cell channel updating information to the neighborNode Bs when notifying a Node B where the user terminal is located toreconfigure the radio link; and the neighbor Node Bs receiving theneighbor cell channel updating information, and updating the informationof the user terminal in the uplink multi-cell joint detectioninformation.
 3. The method according to claim 1, further comprising: theradio network controller sending a neighbor cell channel deletioninformation to the neighbor Node Bs when the Node B application partprotocol process happens at the Iub interface to delete the radio linkof the user terminal; and the neighbor Node Bs deleting the informationof the user terminal in the uplink multi-cell joint detectioninformation after receiving the neighbor cell channel deletioninformation.
 4. The method according to claim 1, wherein the Node Bapplication part protocol process to establish the radio link for theuser terminal includes a radio link setup process or a radio linkaddition process.
 5. The method according to claim 1, wherein theneighbor Node Bs of the cell where the user terminal is located are NodeBs where cells which are found from neighbor cells of the cell where theuser terminal is located are located, the neighbor Node Bs including acell which contains a frequency point at which the established radiolink is present and is the cell where uplink joint detection is requiredto be performed for the user terminal.
 6. The method according to claim1, wherein the neighbor cell channel updating information includes auser terminal identifier as well as a carrier frequency on which theestablished radio link is present and a physical channel occupied by theestablished radio link.
 7. The method according to claim 6, wherein theneighbor cell channel updating information further includes scramblingcodes of the cell where the user terminal is located and a list of cellswhere uplink joint detection is required to be performed by the neighborNode Bs.
 8. The method according to claim 3, wherein the neighbor cellchannel deletion information includes a user terminal identifier.
 9. Themethod according to claim 2, further comprising: the radio networkcontroller sending a neighbor cell channel deletion information to theneighbor Node Bs when the Node B application part protocol processhappens at the Iub interface to delete the radio link_of the userterminal; and the neighbor Node Bs deleting the information of the userterminal in the uplink multi-cell joint detection information afterreceiving the neighbor cell channel deletion information.
 10. The methodaccording to claim 2, wherein the neighbor Node Bs of the cell where theuser terminal is located are Node Bs where cells which are found fromneighbor cells of the cell where the user terminal is located arelocated, the neighbor Node Bs including a cell which contains afrequency point at which the established radio link is present and isthe cell where uplink joint detection is required to be performed forthe user terminal.
 11. The method according to claim 2, wherein theneighbor cell channel updating information includes a user terminalidentifier as well as a carrier frequency on which the established radiolink is present and a physical channel occupied by the established radiolink.